In connection with battery powered headworn communication devices it is previously known to use a switched mode power supply based on a class-D driver and an external LC-lowpass filter. This solution has a good efficiency but suffers from a variety of problems due to the presence of an inductor, which gives rise to magnetic interference, stability problems and in some cases size problems. Another idea is to use a switched capacitor step down converter, which in no-load condition would linearly transform the battery voltage to a fraction of it. In principle, this would have a satisfactory function, however, for battery voltages below a certain voltage the output supply can no longer be guaranteed to be the desired. Low battery voltage may occur gradually or instantaneously (sudden load changes) during lifetime of the battery. A third possibility is to use linear regulators to provide a lower voltage than the battery voltage, however a drawback for such conversion is that the energy efficiency is poor. High efficiency is however a very important aspect for battery operated applications where lifetime of the battery may be crucial for the individual in need of such battery-operated device.
The objective of the invention is therefore to provide a power conversion method and system for battery operated applications, where the energy efficiency is improved compared to previously known linear regulator systems, which does provide a stable power supply and which still is capable of maintaining a sufficient voltage for the battery operated application.